Experimental Measurements and Mathematical Modeling of Cytosolic Ca(2+) Signatures upon Elicitation by Penta-N-acetylchitopentaose Oligosaccharides in Nicotiana tabacum Cell Cultures.

Plants have developed sophisticated recognition systems for different kinds of pathogens. Pathogen-associated molecular patterns (PAMPs) can induce various defense mechanisms, e.g., the production of reactive oxygen species (ROS) as an early event. Plant defense reactions are initiated by a signal transduction cascade involving the release of calcium ions (Ca(2+)) from both external and internal stores to the plant cytoplasm. This work focuses on the analysis of cytosolic Ca(2+) signatures, experimentally and theoretically. Cytosolic Ca(2+) signals were measured in Nicotiana tabacum plant cell cultures after elicitation with penta-N-acetylchitopentaose oligosaccharides (Ch5). In order to allow a mathematical simulation of the elicitor-triggered C(a2)+ release, the Li and Rinzel model was adapted to the situation in plants. The main features of the Ca2+ response, like the specific shape of the C(a2)+ transient and the dose-response relationship, could be reproduced very well. Repeated elicitation of the same cell culture revealed a refractory behavior with respect to the Ca(2+) transients for this condition. Detailed analysis of the obtained data resulted in further modifications of the mathematical model, allowing a predictive simulation of Ch5-induced C(a2)+ transients. The promising results may contribute to a deeper understanding of the underlying mechanisms governing plant defense.